This study demonstrated the dual roles of PMS as a complexing ligand with TiO2 and a precursor of sulfate radical (SO4●−). The activation was enabled by ligand-to-metal charge transfer (LMCT) under visible light irradiation. In this system, the photoexcited TiO2-PMS charge transfer (CT) complex injects the electron from the ligand to the conduction band (CB) of TiO2, which subsequently activate PMS to generate SO4●−. The addition of PMS induced a complete degradation of 4-chlorophenol and dichloroacetate on TiO2 under visible light irradiation, whereas TiO2 and PMS alone lack of visible light absorption. Through several spectroscopic analyses and characterizations, the results revealed that the formation of TiO2-PMS CT complex and the LMCT induced SO4●− production. The production of SO4●− as a main oxidant was confirmed by (1) quenching effect by radical quenchers, (2) coumarin hydroxylation as an indication of SO4●− formation, and (3) EPR spin-trapping technique. Furthermore, multi-activity evaluation revealed that the oxidizing capacity of TiO2/PMS varied depending on the substrate type.

Visible light-induced activation of peroxymonosulfate on TiO2

256th National Meeting (2018)

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